Ischemia hurts. And tourniquets induce ischemia
on purpose. So logically, tourniquet application should hurt. In a hospital
setting, Doppler ultrasound is used to confirm loss of arterial inflow to the
extremity. In the field, the usual end point is cessation of bleeding. The idea
is to stop tightening the moment that bleeding stops. Unfortunately, this is
not very exact. So the next question is, can pain after tourniquet application
be used to predict how well it is working?

The group at Cook County in Chicago measured
pressures, arterial occlusion, and pain in various extremities in a group of
healthy volunteers (!!). Fortunately for them, complete occlusion was only
maintained for a minute.

Here are the factoids:

• Three tourniquet systems were used: an
  in-hospital pneumatic tourniquet, the CAT™, and the SWAT™
• Readings were taken on left and right upper
  arms, the forearms, legs, and the right thigh
• Using a pain scale of 0-10, tourniquet
  application did not generally induce severe pain
• Pain scores were 1-3 in the upper arms and forearms,
  3-4 in the thigh, and 2-3 in the leg

Bottom
line: Strangely enough, tourniquet application did not produce severe pain in
any of the subjects. Thigh application tended to be more painful. But,
generally speaking, pain cannot be used as an indicator of effective
application. In the field, cessation of bleeding is the best indicator. And in
the hospital, Doppler ultrasound confirmation should be the standard. In any
case, if the patient is experiencing undue pain after application, check the tourniquet and its positioning.
Something else might be wrong!

Reference:
Pain is an accurate predictor of tourniquet efficacy. EAST 2016 Poster abstract
#23.